1. Field of the Invention
The present invention relates to a method of manufacturing a light emitting diode (LED) package, more particularly, which allows phosphors of a lattice structure to be formed on a phosphor layer disposed on a light emitting surface of an LED chip of the LED package using an ink jet process, thereby increasing light emitting efficiency of the LED package and simplifying a manufacturing method thereof.
2. Description of the Related Art
A light emitting diode (LED) utilizes a phenomenon in which with a forward voltage applied to electrodes, electrons of a conduction band emit light equivalent to an energy required when transiting to recombine with holes of a valence band. The LED has various advantages over a conventional bulb to be extensively applied to electric and electronic products. That is, the LED is smaller-sized and lighter-weight, less heat-radiating, long in useful life and high in response rate.
Recently, studies have been under way to increase light emitting efficiency of an LED device. One method is to form a structure or a pattern having a predetermined period on a surface of a phosphor in order to enhance light emitting efficiency of the LED device.
That is, to form the phosphor in the LED device, mainly phosphor powder is formed into a slurry or paste to be applied on a flat surface. Here, an irradiated excited light source and light generated by subsequent excitation of the phosphor may be scattered or lost due to the phosphor powder, thereby degrading light emitting efficiency and brightness.
To overcome this problem, there have been efforts to increase light emitting efficiency by forming a lattice structure on the phosphor.
FIG. 1 is a cross-sectional view illustrating a conventional LED package disclosed in Korean Patent Publication No. 2006-0055934.
Referring to FIG. 1, the LED package includes an LED 11, a housing 14 for housing the LED chip therein and an amplifying plate 12 sealing the LED chip.
Reflective plates 14a are formed inside the housing 14 to reflect light from the LED chip 11, and the LED chip 11 is bonded to the housing by wires 18. Also, microstructures 13 are formed on one surface of the amplifying plate 12. The microstructures scatter light emitted from the LED chip to be amplified and emitted. Here, the pitch of the microstructures, depth of furrows and shapes may be varied to ensure light to be maximally refracted through the amplifying plate and thus to be maximally radiated forward.
To form the lattice structure, for example, a photo-sensitive polymer is applied on the phosphor body and then an UV is irradiated to cure a predetermined lattice structure. Then a remaining area other than the lattice structure is etched to form a three-dimensional lattice structure. Alternatively, a photolithography may be employed to form the thin film-shaped phosphor of the lattice structure.
However, when it comes to etching, it is hard to form a periodically uniform lattice structure due to problems associated with light control and resolution. Also, when the thin film-shaped phosphor is formed via photolithography, light generated inside the phosphor is trapped due to total reflection, thereby deteriorating light emitting efficiency.